Refrigerant throttling valve

ABSTRACT

This invention relates to a fluid pressure regulating valve that may be used for a refrigeration system and which includes an inlet, an outlet, and a first interface member therebetween having a plurality of fluid ports. Slidably disposed to be movable relative to the first member is a second interface member, the walls of which also include a plurality of fluid ports. The configuration of the respective fluid ports of the first interface member is different relative to the configuration of the respective ports of the second interface member to thereby perform throttling of the fluid passing therethrough in nonlinear fashion to thus regulate the valve output as the movable member moves from fully open to fully closed valve position.

Carroll et al [451 Feb. 26, 1974 REFRIGERANT THROTTLING VALVE [75]Inventors: Michael 0. Carroll, Rosemont',

Lawrence J. Shirek, Minneapolis, both of Minn.

[73] Assignee: Thermo King Corporation,

Minneapolis, Minn.

[22] Filed: Jan. 23, 1973' [21] Appl. No.: 325,967

[52] US. Cl..... l37/505.26, 137/505.l8, 137/625.3,

[51] Int. Cl. lFl6k 17/34 [58] Field of Search..... 137/505.18, 505.26,625.28,

3,698,204 lO/l972 Schlotterbeck 62/217 X Primary ExaminerHarold W.Weakley Attorney, Agent, or FirmF. E. Blake 5 7 ABSTRACT This inventionrelates to a fluid pressure regulating valve that may be used for arefrigeration system and which includes an inlet, an outlet, and a firstinterface member therebetween having a plurality of fluid ports.Slidably disposed to be movable relative to the first member is a secondinterface member, the walls of which also include a plurality of fluidports. The configuration of the respective fluid ports of the firstinterface member is different relative to the configuration of therespective ports of the second interface member to thereby performthrottling of the fluid passing therethrough in non-linear-fashion tothus regulate the valve output as the movable member moves from fullyopen to fully closed valve position.

4 Claims, 10 Drawing Figures PATENTEB FEB 26 I974 SHEET 1 OF 2 FIG. 2

REFRIGERANT THROTTLING VALVE CROSS REFERENCES TO RELATED APPLICATIONS Sofar as known, this application is not related to any pending patentapplication.

BACKGROUND OF THE INVENTION Commercially available fluid pressureregulating valves that perform throttling of suction gas in arefrigeration system have had problems with stability and chattering.They also have had a wide pressure differential in order to get fullstroke of the valve from opened to closed. Thus, under normal operationthe valve inlet pressure will not be far enough from the valve set pointto open the valve completely, and a pressure drop will be maintainedacross the valve when, ideally, it should be fully opened to avoidcausing a drop in refrigerating capacity. A major design problem withthe construction of conventional valves is that a slug of liquidrefrigerant (freon) can be passed through the valve parts causing thevalve to slam shut momentarily and then return to its original position.When the liquid slug passes from a region of higher pressure to one oflower pressure, it may flash to a vapor and cause large forces resultingin chattering.

It would therefore be desirable to design a fluid valve primarily for arefrigeration system which would perform throttling of the suction gas.It would also be desirable that the valve have large damping forceswhereby quantities of fluid could be passed through without chattering.The valve should be compact in size yet have a high capacity whileproviding a fluid port configuration that insures stability andrelatively narrow pressure differential in order to shift the valve fromfully opened to fully closed.

PRIOR ART Reference may be made to the following US. Pat. whichgenerally'shows a fluid pressure valve for a refrigeration system thatincludes a fixed ported interface sleeve member and a ported pistoninterface member slidably disposed relative to the sleeve: US. Pat. No.2,309,773 Kaufman February, 1943 However, no patent is known whichdiscloses a fluid pressure valve for a refrigeration system in which theconfiguration of the respective fluid ports of one of the interfacemembers is different relative to the configuration of the respectiveports of the other interface member such as to non-linearly regulate theoutput of the valve.

SUMMARY OF THE INVENTION A fluid pressure regulating valve to be usedwithin a refrigeration system is disclosed which is sensitive to onlydownstream suction pressure. The valve comprises an inlet, a fixedcylindrical interface sleeve mem ber having a plurality of fluid ports,and a fluid outlet communicating with the inlet through the sleeveports. Concentrically positioned and slidably disposed relative to thesleeve member is a pressure responsive interface piston member alsohaving a plurality of fluid ports. The piston interface member can bestroked to open or close the valve upon a predetermined downstreampressure.

In accordance with the instant invention, the configuration of therespective ports of one of said interface members is different relativeto the configuration of the respective ports of the other interfacemember. This portarrangement helps to throttle the suction gas when theport area is decreased and non-linearly regulates the valve output asthe piston is stroked from a fully opening through a fully closing ofthe valve.

In one embodiment of the invention, the spacings between the centerlinesof the respective ports of one interface member relating to the spacingsof the respective ports of the other interface member is different. Inan alternate embodiment, the port configuration includes the sizes ofthe respective ports of one interface member relative to the sizes ofthe respective ports of the other interface member being different.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross section view of afluid pressure valve having a port configuration of the presentinvention wide open to fluid flow;

FIG. 2 is a detailed view of the port configuration of FIG. 1;

FIGS. 3 to 5 and 7 to 9 are alternate port configurations of the valveprogressively stroked from fully open to fully closed; and

FIGS. 6 and 10 are diagrammatic representations of the non-linear fluidflow pattern occurring when employing the fluid port configurations ofFIGS. 3 to 5 and 7 to 9 respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, a fluid pressure regulating valve 1 is shown which may haveapplication to the throttling of the suction gas of a refrigerationsystem. Valve 1 has a generally horizontal fluid inlet opening 2 and avertical fluid outlet opening 4. Inlet 2 may be connected in line to theoutlet of a refrigeration evaporator (not shown), and outlet 4 may becon nected between the refrigeration suction line and the inlet of thecompressor (also not shown), with the effect that the valve is situatedwithin the refrigeration system to be responsive to downstream pressureonly (as will later be described) while being insensitive to changes inthe upstream pressure.

A first interface member, taking the form of a stationary cylindricalsleeve 6 in the preferred embodiment, is provided with a plurality offluid ports 9 and is disposed between inlet and outlet openings 2 and 4.The sleeve 6 is secured between valve end members 7 and 8 and defines anannular fluid chamber 10 formed between the valve inlet and outlet.Valve 1 is enclosed by an adjusting cap 12 which is adapted to bescrewed onto threads formed in valve end member 7, as shown.

Pressure sensing in the instant invention is accomplished by aconventional flexible bellows 14 located about a compression-type springmechanism 16 which allows a set point to be established to cause thevalve to be automatically actuated upon a predetermined downstreampressure and thereby prevent the suction pressure at the compressor fromexceeding a maximum limit. The spring mechanism 16, which is supportedby the bellows at the lower end and by a retention boss 18 formed in cap12 at the upper end, enables the set point to be changed by screwingdown adjusting cap 12 and thereby varying the compression of springmechanism 16. Snap ring 20 is provided to limit the bellows travel underhigh pressure conditions.

Attached to the lower end of bellows I4 through a rod 22 is a pressureresponsive, second interface member 24 which, in the preferredembodiment, can be-a piston. The coupling of piston 24 to rod 22 can beeffective to move the piston by action of the bellows 14. Piston 24 isconcentrically fitted and slidably disposed to be movable relative tosleeve interface 6 in order that valve 1 may be opened or closed toregulate the fluid pressure therein, as will be explained more fullyhereinafter. Walls 26 of piston 24 are also provided with a plurality offluid ports 28. Ports 9 and 28 of sleeve interface member 6 and pistoninterface member 24 respectively co-operate to provide means by whichthe valve may operate to perform throttling of the suction fluid.

In accordance with the instant invention, the configuration of therespective ports of one of the interface members is different relativeto the configuration of the respective ports of the other cooperatinginterface memberv By way of example, the port configuration of sleeve 6may be graduated, either progressively or otherwise, relative to theport configuration of movable piston 24 (as generally shown in FIGS. 3to 5), but, it is to be understood that the port configuration of thesliding piston interface walls 26 may also be made suitably differentrelative to the ports of sleeve 6 (as generally shown by FIGS. 7-9).

More particularly, one form of accomplishing fluid throttling is theembodiment illustrated by the port configuration of FIG. 3-5. Ports 9are so disposed in sleeve 6 that the distance between the centerlines ofeach succeeding port is different, while the distance between thecenterlines of each succeeding port 28 of piston walls 26 are maintainedat a constant dimension. An alternate port configuration within thescope of the instant invention and embodied generally in FIGS. 7-9 is tovary the sizes of each succeeding fluid port 28 disposed in piston walls26 while maintaining the size of the ports 9 of sleeve 6 to be one of aconstant dimension.

OPERATION OF FLUID PRESSURE REGULATING VALVE The spring rate of bellowsl6 and the force exerted by the adjusting cap 12 while compressingspring 16 in arriving at a desired setpoint determines the pressure atwhich the'fluid ports of valve 1 cooperate to be fully closed to fluidvBellows 16 may be vented to the atmosphere through an orifice 30 drilledin cap 12 in order to obtain an atmospheric pressure reference. Thepressure on the face of the bellows acts to oppose the force ofcompression spring 16. If the compressor is started up after thepressure in the system has had time to stabilize and at a pressurehigher than the set point of the valve. piston 24 will be initiallydisposed at a position with respect to sleeve 6 such that fluid ports 9and 28 will cooperate to be fully Closed (FIGS. 5 and 9) therebypreventing fluid refrigerant from flowing to the compressor, and piston24 will be bottomed against snap ring 20. After the compressor startsup, the pressure at the valve outlet 4 immediately drops and piston 24will be automatically moved slightly away from snap ring by bellows 14and to such a position with respect to sleeve 6 that fluid ports 9 and28 are now opened sufficiently to maintain the downstream pressure atthe level corresponding to the set point of the valve. Bellows 14 isresponsive to a downstream pressure signal received through a smallorifice 32 in the face of the piston 24, while being non-responsive tothe inlet or upstream pressure. Orifice 32 allows fluid to pass to thebellows at a relatively slow rate, thereby damping the movement ofpiston 24 to prevent the piston from chattering due to forces occurringfrom any rapid changes in the fluid passing from a region of higherpressure to one of lower pressure.

After a continuous running of the refrigeration system, the pressure atthe valve inlet will normally drop below the setpoint. The compressorbecomes able to pump fluid refrigerant at a downstream suction pressurebelow that of the setpoint, and the corresponding pressure of bellows 14will cause piston 24 to be moved further away from snap ring 20. As thedownstream pressure continues below the set point, each of the valveports 9 and 28 will be opened progressively further, but at slightlydifferent points of the piston stroke due to the relatively differentnature of the port configuration of one interface member with respect tothe other. Eventually, a point is reached where the bellows has openedthe ports to a fully open position where both the valve inlet and outletpressure will be below the set point. In a wide opened condition (FIGS.1 and 2), the fluid is free to flow through the valve substantiallyunimpeded, and except for the slight pressure drop caused by friction,the pressure drop across the valve will be eliminated.

The relatively sliding ports 28 in interface piston walls 26 withrespect to the fixed ports of the interface sleeve member 6 cause agradual pressure drop across the valve and a subsequent throttling ofthe suction fluid whenever the fluid port areas are decreased, while therelatively different port configuration of one interface member withrespect to the port configuration of the cooperating interface memberresults in a generally stable valve of the type requiring a narrowpressure differential to stroke the valve from fully closed to fullyopened. The valve can maintain a high flow rating, while the slidingport arrangement provides a means to non-linearly regulate the flow offluid as the piston is moved from a fully opened position to a fullyclosed position of the valve. FIGS. 3 to 5 and FIGS. 7 to 9 show theprogressive movement of sliding piston member 24 with respect to fixedsleeve 6 at positions through which the valve is stroked fully opened tofully closed. FIGS. 6 and 10 diagrammatically represent the nonlinearfluid output pattern 36 of the valve obtainable by means of thealternate port configurations illustrated in FIGS. 3 to 5 and 7 to 9respectively when the piston is moved from a fully opened position to afully closed position of the valve as distinguished from a linear flowoutput 38 obtainable with conventional fluid pressure regulating valves.

The close fit between piston interface member 24 and sleeve interfacemember 6 causes an oil film to be sheared as the piston moves. Thepiston may be fabricated from material having a large mass (i.e., brass)which, together with the viscous drag caused by the shearing of the oilfilm, contributes to restricting the speed of the piston movement tofurther enhance damping and thereby prevent the valve from chattering.Other modifications will occur to those skilled in the art.

We claim:

1. A fluid pressure regulating valve comprising;

an inlet for receiving a fluid under pressure,

a first interface member having a plurality of fluid ports, a fluidoutlet communicating with said inlet by means of said ports, andpressure responsive second interface member hav- 5 ing a plurality offluid ports and being slidably disposed relative to said first member toopen or closed said valve upon a predetermined downstream pressure, theconfiguration of the respective ports of the one of said interfacemembers being different relative to the configuration of the respectiveports of the other interface member to thereby non-linearly regulate theflow of fluid between said inlet and outlet as said second member ismoved from a fully opened position to a fully closed position of saidvalve. 2. The invention of claim 1, wherein the spacings between thecenterlines of the respective ports of the first interface memberrelative to the spacings of the centerlines of the respective ports ofthe second interface member is different.

3. The invention of claim 1, wherein the sizes of the respective portsof the first interface member relative to the sizes of the respectiveports of the second interface member is different.

4. The invention of claim 1, wherein said pressure responsive secondinterface member has an orifice therein and is bellows actuated, saidvalve also including a valve orifice communicating with the atmospheresurrounding the valve, saidvalve orifice providing means to obtain apressure reference for said bellows to cause movement of said secondinterface member to open or close said valve upon a predetermineddownstream pressure, and said second interface member orifice providingmeans through which fluid may pass to said bellows to thereby dampen themovement of said second interface member.

1. A fluid pressure regulating valve comprising; an inlet for receivinga fluid under pressure, a first interface member having a plurality offluid ports, a fluid outlet communicating with said inlet by means ofsaid ports, and a pressure responsive second interface member having aplurality of fluid ports and being slidably disposed relative to saidfirst member to open or closed said valve upon a predetermineddownstream pressure, the configuration of the respective ports of theone of said interface members being different relative to theconfiguration of the respective ports of the other interface member tothereby non-linearly regulate the flow of fluid between said inlet andoutlet as said second member is moved from a fully opened position to afully closed position of said valve.
 2. The invention of claim 1,wherein the spacings between the centerlines of the respective ports ofthe first interface member relative to the spacings of the centerlinesof the respective ports of the second interface member is different. 3.The invention of claim 1, wherein the sizes of the respective ports ofthe first interface member relative to the sizes of the respective portsof the second interface member is different.
 4. The invention of claim1, wherein said pressure responsive second interface member has anorifice therein and is bellows actuated, said valve also including avalve orifice communicating with the atmosphere surrounding the valve,said valve orifice providing means to obtain a pressure reference forsaid bellows to cause movement of said second interface member to openor close said valve upon a predetermined downstream pressure, and saidsecond interface member orifice providing means through which fluid maypass to said bellows to thereby dampen the movement of said secondinterface member.